This type of device is known, for example, from U.S. Pat. No. 5,497,100.
A radar arrangement for street condition recognition in a vehicle is known from WO 98/48296, in which a transmitting-receiving antenna arrangement has an antenna diagram narrowly bundled in the horizontal and vertical direction, which illuminates a roadway section ahead of the vehicle within a distance range between 10 m and 100 m in the travel direction, and in which receiving devices receive echo signals from the illuminated roadway section and derive from them a classification of the roadway condition in the roadway section into stipulated street condition categories. The echo signals are then subdivided in the distance regions and evaluated.
A device for roadway condition recognition in a vehicle is known from WO 01/04659, in which the device for roadway condition recognition illuminates a roadway section ahead of the vehicle within a distance range between 2 m and 200 m in the travel direction and records echo signals, by means of receiving devices, from the illuminated roadway section, in order to derive from them a classification of the roadway condition in the roadway section into stipulated condition categories, in which a millimeter wave radar, having an intended diagram narrowly bundled in the horizontal and vertical direction is combined with an infrared laser radar, in which the millimeter wave radar and the infrared laser radar are aligned on the same roadway section, and in which the millimeter wave radar and the infrared laser radar are connected to a common evaluation unit.
EP 0 470 506 B1 discloses a sensor system for recognition of the surface condition on a roadway, in which an infrared sensor and receiver is formed with filters and linked for combined operation with a microwave transmitter and receiver, in which signals of the infrared or microwave receiver are processed by logic networks and linked to each other via one or more gates, in which condition displays are formed at the output of the gate and the logic network or at the output of the gates, in which, by means of an XOR gate, the individual state displays are checked for their logic condition correctness, and the result, in turn, is displayed via its own condition display.
The task of the invention is to provide an improved device for determination of the surface condition of a roadway.